Drawing instrument



March 13, 1951 J. T. SHERIDAN 2,545,112

DRAWING INSTRUMENT Filed Sept. 23, 1949 2 Sheets-Sheet 1 Fig.

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIILIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII n mIZIMLEIRALnZImIIIIII-I IIIIIII --------I Inventor John 7'. Sheridan March 13, 1951 J. T. SHERIDAN 2,545,112

DRAWING INSTRUMENT Filed Sept. 23, 1949 2 Sheets-Sheet 2 In ventar John T. Sheridan (wi way EM L Patented Mar. 13, 1951 UNITED STATES PATENT OFFICE DRAWING INSTRUMENT John .T. Sheridan, Columbia, 111. Application'S eptember 23, 1949, Serial No. 117,455

3 Claims. 1

This invention relates to new and usefulv impicvements in drawing instruments and the primary object of the present invention is to provide adrafting instrument including a T-square having a rotatable head and a protractor on the head whereby lines at any suitable angle may be scribed upon a drawing.

Another important object of the present invention is to provide a T-square including astraight edge and a. protractor supporting head pivoted to the straight edge for rotation, and embodying a novel and. improved means for guiding rotation of the head relative to the straight edge.

A further object. of the present invention is to provide a drawing instrument including a plurality of. parts that are quickly and readily assembled or disassembled in a convenient manner facilitating storage, shipment or replacement of parts.

A still further aim of the present invention is to provide an instrument of the aforementioned character that is simple and practical in construction, strong and reliable in use, efficient and reliable in operation, relatively inexpensive to manufacture, and otherwise well adapted for the purposes for which the same is intended.

Other objects and advantages reside in the details of. construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure l is a plan View of the present invention arranged for drawing horizontal lines on a drawing sheet;

Figur 2 is an enlarged longitudinal vertical section view taken substantially on the plane of section line 2-2 of Figure l and showing a drafting board in dotted lines abutting one of the cross members and underlying th straight edge;

Figure 3 is an enlarged fragmentary view of Figure l with the, non-rotatable cross member removed therefrom;

Figure 4 is a fragmentary top plan view of the non-rotatable cross member;

Figure 5 is a fragmentary bottom plan View of the non-rotatable cross member of Figure 4;

Figure 6 is a side view of Figure 4 taken substantially in the direction of the arrow numbered 6;

Figure '7 is a side view of the rotatable head;

Figure 8 is a fragmentary plan view of the outer plate used with the rotatable cross-head;

Figure 9 is a fragmentary plan view of the inner plate used with the rotatable cross-head; and

2 Figures 0 and 11 are perspective views of'th fasteners used in conjunction with the present invention.

Referring now to the drawings in detail, wherein for the purpose of illustration there is disclosed a preferred embodiment of the present invention, the numeral 10 represents a rotatable cross-head or member generally, including a. main body portion or central plate 52, an outer circular plate It an inner circular plate L6; The main. body portion I2 is elongated and its central portion is provided with circular recesses inv both of its faces that receive the plates [.4 and it.

One edge it of the body portion [2: is straight and the plates Hland 16 are cut so that the same will include edges 20 and 22 which are'flushwith the straight edge l of the body portion t2. Each of the plates It and iii are provided with a plurality of cireumferentially spaced apertures 24 that receive fasteners 25 securing the plates l4 and iii to th body portion I2.

The body portion i2 is formed with a transverse opening 28, perpendicular to the body portion l2, that receives the end portion 30 of an, elongated, substantially rectangular, straight edge 32 having suitable graduations or scales 34 thereon. The undersurface of the. end portion. 30 is provided with a recess forming a transverse shoulder 36 against which the edge 2.2 of plate It abuts, as shown best in Figure 20f the drawings.

Th rotatable. cross-head is associated. with a non-rotatable cross-head or member 318 including an elongated main body portion 48-, and inner. and outer, substantially circular plates 4?v and 44. The faces of the body portion 4E1, at the central portion thereof, are provided with circular recesses in which the plates 4'2 and 44 are seated. The plates 42 and 44 are secured to the body portions M3 by a plurality of circumferentially spaced fasteners 46 that extend through aperturesAS in the platestoextend into the body portion 49.

The body portion dB issimilar in. shape and constructionto the body portion l2 and therefore includes a straight inner edge 50. The plates 42 and 4.4 are also notched to. provide edges 52' and 54: that are flush with the. edge 50 of the body portion 46. When the, instant. instrument-or T- square is in use, the edges 50, 5:2 and; 54 will bear against one edge of a drawing board 56 or table as shown inFigure'2.

Means is provided for pivotally or rotatably securing the cross-heads together whereby the cross-head ill and the straight edge 32 may rotate about the cross-head 38 when the latter is placed against one edge of a drawing board as shown in Figure 2. This means consists of a pivot or bolt 58 that extends through the central portions of the body portion [2, l4, and the plates l4, i6, 42. The head portion 68 of the bolt 58 is seated in a recess in the lowe or outer face of the body portions 40 and is held therein by the plate 44.

The threaded end of the bolt 58 projects out- Wardly from the plate I i and a finger gripping knob or nut 62 is threaded thereon for clamping the cross-heads together to retain the cross-head In in a selected rotated position relative to the cross-head 38.

Means is provided for guiding the cross-head In during rotation thereof relative to the crosshead 38 and for limiting rotation of the crosshead it) with respect to the cross-head 38. This means comprises a guide and stop bolt 64 that extends through registering arcuate slots 65 in the body portion 40 and the plate 42. The bolt 64 is spaced parallel to th pivot 58 and in alignment with the axis of the straight edge 32.

The lower or outer face of the body portion 45 is provided with an arcuate guide channel or groove 66 that slidably receives th head 68 of the bolt 64. The threaded shank of the bolt 54 projects upwardly through registering openings 69, H, 13 and 15 in the plate M, the body portion I2, the end portion 30 and th plate 16 respectively, and outwardly from the plate 14 and receivably engages a finger gripping knob or nut '10 for holding the cross-head 38 in a selected rotated position relative to the cross-head Hi.

The plate 12 constitutes a protractor and is consequently provided with angle graduations l2 thereon. Diametrically opposite from the straight edges l8 of th body portion l2, the body portion l2 and plates M and it are notched to provide a concave recess 14 that permits visibility of the graduations 12 on the plate 42. A pointer or lug 16 extends radially from the notch in plate [6 for registering with the indicia or graduations 12 thereby permitting the cross-head l and the straight edge}? to be rotated to a selected angle with the cross-head 38.

In view of the foregoing description taken in conjunction with the accompanying drawings it is believed that a clear understanding of the construction, operation and advantages of the de- Vice will be quite apparent to those skilled in this art. A more detailed description is accordingly deemed unnecessary.

It is to be understood, however, that even though there is herein shown and described a preferred embodiment of the invention the same is susceptible to certain changes fully comprehended by the spirit of the invention as herein described and the scope of the appended claims.

Having described the invention, what is claimed as new is:

1. A drafting instrument comprising first and second cross-heads, a straight edge secured to said first head and disposed perpendicular to said first head, a pivot securing the cross-heads together, a protractor mounted on said second cross-head, a pointer on said first cross-head for registering with the protractor, a bolt extending through said straight edge and said cross-heads for guiding the rotation of the first cross-head relative to the second cross-head about the pivot, a holding nut threaded on said bolt for retaining the first cross-head in a selected rotated position about the pivot, said second cross-head having an arcuate slot therein, said slot being substantially key shaped in cross section with the enlarged portion of the slot at the underside of the second cross-head, and a plate secured to the underside of said second cross-head and concealing said slot and preventing foreign matter from collecting in said slot, said bolt having a multisided head slidably and non-rotatably received in the enlarged portion of said slot.

2. A drafting instrument comprising first and second cross-heads, a straight edge secured to said first cross-head and disposed perpendicular to said first head, a pivot securing the crossheads together, a protractor mounted on said second cross-head, a pointer on said first crosshead for registering with th protractor, means for guiding the rotation of the first cross-head relative to the second cross-head about the pivot, said second cross-head having an arcuate slot in it lower face, said guide means comprising a bolt carried by said cross-heads and having a head portion received in the arcuate slot, said bolt having a threaded portion projecting outwardly from first said cross-head, a holding nut threaded on the threaded portion of said bolt for bearing against the first head to retain the first 'crosshead in a selected rotated position about the pivot, and a cover plate secured to the undersurface of said second cross-head and concealing the arcuate slot.

3. A protractor attachment for straight edges, said attachment comprising first and second cross-members having central openings, said openings being in registry, a pivot pin received in said openings, said first cross-member having a slot therein intersecting the opening in said first cross-member and adapted to receive one end of a straight edge, said first cross-member having inner and outer faces, an inner plate secured to the inner 'face of said first cross-member, an outer plate secured to the outer face of said first cross-member, said inner plate having a radially projecting pointer thereon, said outer plate having a notch in registry with the pointer, said second cross-member having an inner face, a protractor mounted on the inner face of said second cross-member for registry with the pointer on the inner plate, said second crossmember having an arcuate slot therein, said arcuate slot being substantially key-shaped in cross section to include a main portion and an enlarged portion, a bolt having its head portion received in the enlarged portion of said arcuate slot, said first cross-member having an aperture receiving said bolt, and a nut threaded on said bolt for hearing against the outer plate to retain the first cross-member in a selected rotated position about the pivot.

JOHN T. SHERIDAN.

REFEREIQCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,561 Card Apr. 16, 1342 404,451 Waggoner June 4, 1889 797,228 Robinson Aug. 15, 1905 1,230,901 Houghton June 26, 1917 2,104,354 Rich Jan. 4, 1938 

